1. Field
The following description relates to a method of transmitting and receiving data using a wireless network.
2. Description of Related Art
In a space division multi-user multiple input multiple output (SD-MIMO) communication method, precoding may correspond to a process of appropriately allocating spatial beams to users.
Multiple-input and multiple-output (MIMO) includes three main categories: precoding, spatial multiplexing or SM, and diversity coding. Beamforming increases the signal gain from constructive interference and reduces the multipath fading effect. When the receiver has multiple antennas, precoding is used to simultaneously maximize the signal level at the receiving antennas. In spatial multiplexing, a high rate signal is split into multiple lower rate streams, and each stream is transmitted from a different transmit antenna in the same frequency channel. In diversity coding, a single stream is coded using space-time coding and transmitted. Spatial multiplexing can also be combined with precoding or combined with diversity coding.
A transmission apparatus may receive channel status information from terminals, and may select a terminal to receive data using precoding based on the received channel status information. The transmission apparatus may perform precoding based on the channel status information.
A terminal may receive a training signal from the transmission apparatus, and estimate a channel between the transmission apparatus and the terminal using the received training signal to generate channel status information.
In the SD-MIMO communication method, the transmission apparatus may employ a plurality of transmit antennas and thus the channel between the transmission apparatus and the terminal may be provided in a vector or matrix form. To estimate the channel in the vector or matrix form, the transmission apparatus may transmit an individual training signal for each transmit antenna.